PROJECT SUMMARY! ! This application requests funding for the renewal of our NIDA-funded one-year intensive addiction research training fellowship for addiction medicine clinicians. Despite the enormous burden of disease attributable to drug and alcohol addiction, there remain major challenges in implementing evidence-based prevention and treatment modalities for substance use disorders. Low levels of understanding of addiction science among addiction care providers also creates barriers to the implementation of evidence-based public health programs. The unprecedented rise in opioid overdose deaths in North America and HIV outbreaks linked to the opioid epidemic in several regions underscore a pressing need to bridge the evidence-to-practice gap as critical to the response. This provides the rationale for our fellowship program and our desire to extend and expand our fellowship program, already proven to be highly successful at training a substantial number of highly productive young clinician scientists. The International Collaborative Addiction Medicine Research Fellowship provides a flexible, well-established learning environment with a multidisciplinary and international team of 21 highly productive researchers who are committed to training the next generation of addiction clinician scientists. It builds upon a well-established NIDA-funded research infrastructure involving evaluation of unique interventions being implemented in the context of a severe local fentanyl-related opioid epidemic. Furthermore, the fellowship provides addiction medicine clinicians with research methods training, education in the ethical conduct of research, peer-reviewed publication and funding proposal development, presentation skills, and career development training critical for designing and conducting studies on substance use disorders and related comorbidities, including the prevention and treatment of HIV among substance users. Finally, the fellowship includes the continuation of a rigorous prospective evaluation showing how a dedicated research training program for addiction medicine physicians contributes to subsequent ongoing research involvement and research productivity among the next generation of clinician scientists working in the area of substance use disorders. The fellowship has already proven to be well-received and highly successful (as measured by candidates' first-author publications) over the past four years, and the resources and range of clinical trials and educational activities have expanded significantly since the initiation of this addiction medicine fellowship program in 2014. With a growing network of highly regarded interdisciplinary researchers in various fields of addiction medicine with whom fellows can work, we are excited about the possibility of renewing this fellowship so that it can continue to expand the delivery of evidence-based treatment in the field of addiction medicine. This proposal responds directly to the US National Institute on Drug Abuse's expressed ?strong interest in supporting the development of clinical research expertise internationally.? Accordingly, the work proposed herein is strongly aligned with the NIDA International Program's call for research education for addiction medicine physicians.